using System;

/*
 * Copyright 2008 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

namespace iTextSharp.text.pdf.qrcode;

/**
 * @author satorux@google.com (Satoru Takabayashi) - creator
 * @author dswitkin@google.com (Daniel Switkin) - ported from C++
 */
public sealed class MaskUtil
{
    private MaskUtil()
    {
        // do nothing
    }

    // Apply mask penalty rule 1 and return the penalty. Find repetitive cells with the same color and
    // give penalty to them. Example: 00000 or 11111.
    public static int ApplyMaskPenaltyRule1(ByteMatrix matrix) =>
        ApplyMaskPenaltyRule1Internal(matrix, true) + ApplyMaskPenaltyRule1Internal(matrix, false);

    // Apply mask penalty rule 2 and return the penalty. Find 2x2 blocks with the same color and give
    // penalty to them.
    public static int ApplyMaskPenaltyRule2(ByteMatrix matrix)
    {
        var penalty = 0;
        var array = matrix.GetArray();
        var width = matrix.GetWidth();
        var height = matrix.GetHeight();
        for (var y = 0; y < height - 1; ++y)
        {
            for (var x = 0; x < width - 1; ++x)
            {
                int value = array[y][x];
                if (value == array[y][x + 1] && value == array[y + 1][x] && value == array[y + 1][x + 1])
                {
                    penalty += 3;
                }
            }
        }

        return penalty;
    }

    // Apply mask penalty rule 3 and return the penalty. Find consecutive cells of 00001011101 or
    // 10111010000, and give penalty to them.  If we find patterns like 000010111010000, we give
    // penalties twice (i.e. 40 * 2).
    public static int ApplyMaskPenaltyRule3(ByteMatrix matrix)
    {
        var penalty = 0;
        var array = matrix.GetArray();
        var width = matrix.GetWidth();
        var height = matrix.GetHeight();
        for (var y = 0; y < height; ++y)
        {
            for (var x = 0; x < width; ++x)
            {
                // Tried to simplify following conditions but failed.
                if (x + 6 < width &&
                    array[y][x] == 1 &&
                    array[y][x + 1] == 0 &&
                    array[y][x + 2] == 1 &&
                    array[y][x + 3] == 1 &&
                    array[y][x + 4] == 1 &&
                    array[y][x + 5] == 0 &&
                    array[y][x + 6] == 1 &&
                    ((x + 10 < width &&
                      array[y][x + 7] == 0 &&
                      array[y][x + 8] == 0 &&
                      array[y][x + 9] == 0 &&
                      array[y][x + 10] == 0) ||
                     (x - 4 >= 0 &&
                      array[y][x - 1] == 0 &&
                      array[y][x - 2] == 0 &&
                      array[y][x - 3] == 0 &&
                      array[y][x - 4] == 0)))
                {
                    penalty += 40;
                }

                if (y + 6 < height &&
                    array[y][x] == 1 &&
                    array[y + 1][x] == 0 &&
                    array[y + 2][x] == 1 &&
                    array[y + 3][x] == 1 &&
                    array[y + 4][x] == 1 &&
                    array[y + 5][x] == 0 &&
                    array[y + 6][x] == 1 &&
                    ((y + 10 < height &&
                      array[y + 7][x] == 0 &&
                      array[y + 8][x] == 0 &&
                      array[y + 9][x] == 0 &&
                      array[y + 10][x] == 0) ||
                     (y - 4 >= 0 &&
                      array[y - 1][x] == 0 &&
                      array[y - 2][x] == 0 &&
                      array[y - 3][x] == 0 &&
                      array[y - 4][x] == 0)))
                {
                    penalty += 40;
                }
            }
        }

        return penalty;
    }

    // Apply mask penalty rule 4 and return the penalty. Calculate the ratio of dark cells and give
    // penalty if the ratio is far from 50%. It gives 10 penalty for 5% distance. Examples:
    // -   0% => 100
    // -  40% =>  20
    // -  45% =>  10
    // -  50% =>   0
    // -  55% =>  10
    // -  55% =>  20
    // - 100% => 100
    public static int ApplyMaskPenaltyRule4(ByteMatrix matrix)
    {
        var numDarkCells = 0;
        var array = matrix.GetArray();
        var width = matrix.GetWidth();
        var height = matrix.GetHeight();
        for (var y = 0; y < height; ++y)
        {
            for (var x = 0; x < width; ++x)
            {
                if (array[y][x] == 1)
                {
                    numDarkCells += 1;
                }
            }
        }

        var numTotalCells = matrix.GetHeight() * matrix.GetWidth();
        var darkRatio = (double)numDarkCells / numTotalCells;
        return Math.Abs((int)(darkRatio * 100 - 50)) / 5 * 10;
    }

    // Return the mask bit for "getMaskPattern" at "x" and "y". See 8.8 of JISX0510:2004 for mask
    // pattern conditions.
    public static bool GetDataMaskBit(int maskPattern, int x, int y)
    {
        if (!QRCode.IsValidMaskPattern(maskPattern))
        {
            throw new ArgumentException("Invalid mask pattern");
        }

        int intermediate, temp;
        switch (maskPattern)
        {
            case 0:
                intermediate = (y + x) & 0x1;
                break;
            case 1:
                intermediate = y & 0x1;
                break;
            case 2:
                intermediate = x % 3;
                break;
            case 3:
                intermediate = (y + x) % 3;
                break;
            case 4:
                intermediate = ((y >> 1) + x / 3) & 0x1;
                break;
            case 5:
                temp = y * x;
                intermediate = (temp & 0x1) + temp % 3;
                break;
            case 6:
                temp = y * x;
                intermediate = ((temp & 0x1) + temp % 3) & 0x1;
                break;
            case 7:
                temp = y * x;
                intermediate = (temp % 3 + ((y + x) & 0x1)) & 0x1;
                break;
            default:
                throw new ArgumentException("Invalid mask pattern: " + maskPattern);
        }

        return intermediate == 0;
    }

    // Helper function for applyMaskPenaltyRule1. We need this for doing this calculation in both
    // vertical and horizontal orders respectively.
    private static int ApplyMaskPenaltyRule1Internal(ByteMatrix matrix, bool isHorizontal)
    {
        var penalty = 0;
        var numSameBitCells = 0;
        var prevBit = -1;
        // Horizontal mode:
        //   for (int i = 0; i < matrix.Height(); ++i) {
        //     for (int j = 0; j < matrix.Width(); ++j) {
        //       int bit = matrix.Get(i, j);
        // Vertical mode:
        //   for (int i = 0; i < matrix.Width(); ++i) {
        //     for (int j = 0; j < matrix.Height(); ++j) {
        //       int bit = matrix.Get(j, i);
        var iLimit = isHorizontal ? matrix.GetHeight() : matrix.GetWidth();
        var jLimit = isHorizontal ? matrix.GetWidth() : matrix.GetHeight();
        var array = matrix.GetArray();
        for (var i = 0; i < iLimit; ++i)
        {
            for (var j = 0; j < jLimit; ++j)
            {
                int bit = isHorizontal ? array[i][j] : array[j][i];
                if (bit == prevBit)
                {
                    numSameBitCells += 1;
                    // Found five repetitive cells with the same color (bit).
                    // We'll give penalty of 3.
                    if (numSameBitCells == 5)
                    {
                        penalty += 3;
                    }
                    else if (numSameBitCells > 5)
                    {
                        // After five repetitive cells, we'll add the penalty one
                        // by one.
                        penalty += 1;
                    }
                }
                else
                {
                    numSameBitCells = 1; // Include the cell itself.
                    prevBit = bit;
                }
            }

            numSameBitCells = 0; // Clear at each row/column.
        }

        return penalty;
    }
}